I saw this when little, at the very dawn of the VHS age, so I'd guess it was made 70s or very early 80s.

I remember only a couple of scenes.

A white man and a white woman have sex in a barn. This was probably the first time I saw full-frontal nudity in a movie, or had even suspected there was such a thing.

A slave was caught peeping on a white woman (perhaps in the aforementioned scene). Anyway, two white men whip him to pieces with bullwhips then make a big deal of throwing salt in the cuts. I think the only reason they don't kill him is because someone else (possibly the white woman he peeped?) arrives and tells them they're wasting good money if they kill such a strong slave.

Later, one of the white men (the blonde one, I think) rapes (or tries to rape) one of the black maids while she's serving him coffee, or tea, or something. He pulls down the front of her dress and bites one of her nipples, at any rate. I want to think it was in further retaliation for the slave peeping on the white woman, like the maid was his wife, or sister, or something like that. I also want to think he stops because he's ashamed to be enjoying touching a black woman.

At this point, my family must have finally decided I didn't need to watch this and sent me away because I have no further memories.

I haven't watched it since it first came out back in 1977, so I don't recall if it had any of those specific scenes you mentioned, but it does have black slaves, frontal nudity, rape and lots of whipping.

Holy cow! I searched for "Mandingo". I didn't find out if it was the movie or not but, apparently, there is a porn star with a frighteningly large penis who works under that name.

Let's not give Trevor any ideas, but "Mandingo,' though I have never seen it, would be my guess. And if it's not "Mandingo," it might be its sequel "Drum," which came out in 1976 or the year after "Mandingo" was released.